1. Field of the Invention
The present invention relates to a thiophene derivative having a long conjugated chain at the 3-position thereof, and to a material capable of responding to light (hereinafter referred to as photo-responsive material) employing the thiophene derivative. More particularly, the present invention relates to a thiophene derivative which has a long conjugated chain at the 3-position and isomerizes, by light irradiation, reversibly to only one other isomer having light-absorption bands and light-emission bands greatly different from those of the original isomer, and a photo-responsive material employing the thiophene derivative.
2. Related Background Art
Heretofore photo-responsive materials utilizing isomerization caused by light irradiation are known, including vitamin A (or retinal) derivatives, carotene derivatives, azo dye derivatives, and the like.
Among the above photo-responsive materials, vitamin A derivatives and carotene derivatives are disadvantageous in that four or more isomers are formed on light irradiation, and azo dye derivatives are disadvantageous in that the absorption wavelength changes caused by isomerization on light irradiation are small, which makes identification of the respective isomers difficult.